#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <time.h>

#define OK 1
#define ERROR 0
#define TRUE 1
#define FALSE 0
#define MAXSIZE 20 /* 存储空间初始分配量 */

typedef int Status;
typedef int SElemType; /* SElemType类型根据实际情况而定，这里假设为int */


/* 链栈结构 */
typedef struct StackNode {
    SElemType data;
    struct StackNode *next;
} StackNode, *LinkStackPtr;


typedef struct {
    LinkStackPtr top;
    int count;
} LinkStack;

Status visit(SElemType c) {
    printf("%d ", c);
    return OK;
}

/*  构造一个空栈S */
Status InitStack(LinkStack *S) {
    S->top = (LinkStackPtr) malloc(sizeof(StackNode));
    if (!S->top)
        return ERROR;
    S->top = NULL;
    S->count = 0;
    return OK;
}

/* 把S置为空栈 */
Status ClearStack(LinkStack *S) {
    LinkStackPtr p, q;
    p = S->top;
    while (p) {
        q = p;
        p = p->next;
        free(q);
    }
    S->count = 0;
    return OK;
}

/* 若栈S为空栈，则返回TRUE，否则返回FALSE */
Status StackEmpty(LinkStack S) {
    if (S.count == 0)
        return TRUE;
    else
        return FALSE;
}

/* 返回S的元素个数，即栈的长度 */
int StackLength(LinkStack S) {
    return S.count;
}

/* 若栈不空，则用e返回S的栈顶元素，并返回OK；否则返回ERROR */
Status GetTop(LinkStack S, SElemType *e) {
    if (S.top == NULL)
        return ERROR;
    else
        *e = S.top->data;
    return OK;
}

/* 插入元素e为新的栈顶元素 */
Status Push(LinkStack *S, SElemType e) {
    LinkStackPtr s = (LinkStackPtr) malloc(sizeof(StackNode));
    s->data = e;
    s->next = S->top;    /* 把当前的栈顶元素赋值给新结点的直接后继，见图中① */
    S->top = s;         /* 将新的结点s赋值给栈顶指针，见图中② */
    S->count++;
    return OK;
}

/* 若栈不空，则删除S的栈顶元素，用e返回其值，并返回OK；否则返回ERROR */
Status Pop(LinkStack *S, SElemType *e) {
    LinkStackPtr p;
    if (StackEmpty(*S))
        return ERROR;
    *e = S->top->data;
    p = S->top;                    /* 将栈顶结点赋值给p，见图中③ */
    S->top = S->top->next;    /* 使得栈顶指针下移一位，指向后一结点，见图中④ */
    free(p);                    /* 释放结点p */
    S->count--;
    return OK;
}

Status StackTraverse(LinkStack S) {
    LinkStackPtr p;
    p = S.top;
    while (p) {
        visit(p->data);
        p = p->next;
    }
    printf("\n");
    return OK;
}

int main() {
    int j;
    LinkStack s;
    int e;
    if (InitStack(&s) == OK)
        for (j = 1; j <= 10; j++)
            Push(&s, j);
    printf("栈中元素依次为：");
    StackTraverse(s);
    Pop(&s, &e);
    printf("弹出的栈顶元素 e=%d\n", e);
    printf("栈空否：%d(1:空 0:否)\n", StackEmpty(s));
    GetTop(s, &e);
    printf("栈顶元素 e=%d 栈的长度为%d\n", e, StackLength(s));
    ClearStack(&s);
    printf("清空栈后，栈空否：%d(1:空 0:否)\n", StackEmpty(s));
    return 0;
}